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 Remote ATU 
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Post Remote ATU
Right peoples thinking caps on

Looking at making a remote ATU to run me LF tri band antenna inverted L thats at home and take with me portable as well same antenna and prob run me vertical 160 antenna portable too.

Silly things what parts do it need such ad Vari cap and other parts etc even simple diagrams be good too.
Feel this is even more better way to improve the station and at same time build something.

Thanks for any input


2E0FEH


Sat Nov 16, 2019 9:54 am
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 Remote ATU 
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Post Re: Remote ATU
2E0FEH wrote:
Right peoples thinking caps on

Looking at making a remote ATU to run me LF tri band antenna inverted L thats at home and take with me portable as well same antenna and prob run me vertical 160 antenna portable too.

Silly things what parts do it need such ad Vari cap and other parts etc even simple diagrams be good too.
Feel this is even more better way to improve the station and at same time build something.

Thanks for any input


2E0FEH



You can use RC servos to turn the capacitors, and a large metal geared on will turn heavy switches.

Or you can have a bank of 8 relays for the capacitors and inductors, ans use a PIC or similar to switch them, that way you can have memories for the bands as well. Using latching relays would mean it would use no current once tuned.
One simple step further, and you can have the PIC measure the SWR and change the relays, ie an automatic tuner.

RC servos work well, but you have to RF proof them and a good idea to remove the supply from them when transmitting.

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Sat Nov 16, 2019 10:33 am
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 Remote ATU 
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Post Re: Remote ATU
Think about the capacitors being used first of all as this will dictate cost and overall design.

End fed antennas present a very high impedance, so you need to decide what is best from an ATU design config e.g. L-Match, T-Match etc and choose for lowest loss, a good radial ground system is defiantly a key component here too but all these components are systematic to a good antenna system.
The most complex part of the system will be your motor drive and control system, there are many off the shelf systems using Arduino Micro-controllers and high frequency motor drives, you need a simple clutch (Strip down an cheap battery powered drill with a Torque setting maybe?) and the ability detect end stops to feedback to the controller to stop the motors when the VC has reached the min/max rotation, unless of course you choose a butterfly capacitor then this negates the need for detecting end-stop.
Are you going to use the VSWR meter in the shack to determine when you have a match? Maybe you want to read VSWR at the ATU end of the coax and feed this back to the micro-controller for automatic matching.

Lots of food for thought, depends what sort of budget and technical skills you have.

Rob.


Sat Nov 16, 2019 10:38 am
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 Remote ATU 
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Post Re: Remote ATU
You could get something like a FC757 which will auto tune, and remanufacture it as a remote unit

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Sat Nov 16, 2019 10:46 am
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